Older age produces numerous changes in cognitive processes, including slowing in the rate of mental processing speed. There has been controversy over the past three decades about whether this slowing is a result of a decline in processing efficiency or a change in the way information is processed. Research has shown that older adults exhibit a decrease in processing speed, which can be attributed to a variety of factors, including a decline in neural resources, a decrease in the speed of neural transmission, and an increase in the time it takes for information to be processed. This decrease in processing speed can have significant consequences, including a decrease in cognitive performance and an increase in the risk of cognitive decline. Understanding the underlying mechanisms of response-specific slowing in older age is crucial for the development of effective interventions to mitigate its effects and promote healthy aging.